Differences in the profile of neonatal abstinence syndrome signs in methadone- versus buprenorphine-exposed neonates

Abstract

Aims: To compare the profile of signs of neonatal abstinence syndrome (NAS) in methadone- versus buprenorphine-exposed infants.

Design, setting and participants: Secondary analysis of NAS data from a multi-site, double-blind, double-dummy, flexible-dosing, randomized clinical trial. Data from a total of 129 neonates born to opioid-dependent women who had been assigned to receive methadone or buprenorphine treatment during pregnancy were examined.

Measurements: For 10 days after delivery, neonates (methadone = 72, buprenorphine = 57) were assessed regularly using a 19-item modified Finnegan scale. Data from neonates who required pharmacological treatment (methadone = 41, buprenorphine = 27) were included up to the time treatment was initiated. The incidence and mean severity of the total NAS score and each individual sign of NAS were calculated and compared between medication conditions, as was the median time until morphine treatment initiation among treated infants in each condition.

Findings: Two NAS signs (undisturbed tremors and hyperactive Moro reflex) were observed significantly more frequently in methadone-exposed neonates and three (nasal stuffiness, sneezing, loose stools) were observed more frequently in buprenorphine-exposed neonates. Mean severity scores on the total NAS score and five individual signs (disturbed and undisturbed tremors, hyperactive Moro reflex, excessive irritability, failure to thrive) were significantly higher among methadone-exposed neonates, while sneezing was higher among buprenorphine-exposed neonates. Among treated neonates, methadone-exposed infants required treatment significantly earlier than buprenorphine-exposed infants (36 versus 59 hours postnatal, respectively).

Conclusions: The profile of neonatal abstinence syndrome differs in methadone- versus buprenorphine-exposed neonates, with significant differences in incidence, severity and treatment initiation time. Overall, methadone-exposed neonates have a more severe neonatal abstinence syndrome.

Trial registration: ClinicalTrials.gov NCT00271219.

© 2012 The Authors, Addiction © 2012 Society for the Study of Addiction.

Figures

Figure 1

Least square (LS) means (± standard error) of the total neonatal abstinence syndrome (NAS) score in methadone- and buprenorphine-exposed neonates from birth to 240 hours postnatal (PN). The figure illustrates significant main effects of medication condition and of time (Ps < 0.05). The numerical range after the title indicates the minimum and maximum score for the total score. The y-axis is presented on a smaller scale to allow for more detailed inspection of the data

Figure 2

Least square (LS) means (± standard error) of the total neonatal abstinence syndrome (NAS) in methadone- and buprenorphine-exposed neonates from birth to 240 hours postnatal (PN). A ‘0’ was plotted for time-points where the LS mean was negative. All figures illustrate significant main effects of medication condition and of time (Ps < 0.05). The numerical range after the name of each individual sign indicates the minimum and maximum score for that sign. The y-axis is presented on a smaller scale for most signs to allow for more detailed inspection of the data